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May 31, 2011

Woolly Mammoth Hybrid Discovered

by Sam Savage

Researchers said that the woolly mammoth may have mated with a much larger elephant species.

Woolly mammoths roamed the planet for over a million years, ranging from Europe to Asia to North America. Nearly all these mammals vanished from Siberia about 10,000 years ago, although dwarf mammoths survived until 3,700 years ago.

Although woolly mammoths lived in the cold of the tundra, the Columbia mammoth preferred the more temperate regions of southern and central North America.

"We are talking about two very physically different species here," researcher Hendrik Poinar, an evolutionary geneticist at McMaster University in Hamilton, Canada, said in a statement.

"You have roughly 1 million years of separation between the two, with the Columbian mammoth likely derived from an early migration into North America approximately 1.5 million years ago, and their woolly counterparts immigrating to North America some 400,000 years ago."

The researchers investigated the evolution of Columbian mammoths by analyzing DNA retrieved from the tusks, bone and teeth of two 11,000-year-old fossil specimens.

The team concentrated on the genomes of the mitochondria, which have their own unique DNA and are inherited from the mother.

They found the mitochondrial genome of the Columbian mammoth was nearly indiscernible from its northern woolly counterparts.

The researchers said they could not explain the extensive genetic evidence they uncovered, and they replicated their results in an independent lab.

"We think we may be looking at a genetic hybrid," researcher Jacob Enk, a graduate student in the McMaster Ancient DNA Center, said in a statement.

"Living African elephant species hybridize where their ranges overlap, with the bigger species out-competing the smaller for mates," Enk added.

Since woollies and Columbians overlapped in time and space, it is likely they interbreed the same manner.

"It reminds me a bit of high-school days -- the larger males are more successful at meeting women across the dance floor than the rest of us," Poinar said.

The findings could explain why some mammoth fossils feature intermediate between woollies and Columbians.

The researchers want to look at Columbian mammoth specimens from farther south where no woollies venture to help and get idea of what nonhybrid samples looked like.

The scientists' findings were published online May 31 in the journal Genome Biology.